1. Field of the Invention
This invention relates to a robot installation for performing a plurality of operations, e.g., for assembling a plurality of preferably differently shaped parts in a product or for machining a part or parts with a plurality of different tools and/or in several steps.
During the assembly of a plurality of parts of a product at an assembly station with the aid of a robot, the picking up of parts from a magazine and the transportation of the parts to the assembly station may involve long and time-consuming movements for the robot. These very transporting movements may influence or determine the rate of production of the product since the actual fitting of the parts into an assembly fixture or into other parts at the assembly station may be carried out comparatively rapidly. If, in addition, the majority of the parts to be assembled are so different that they require special grippers, it is necessary to provide one robot or one robot arm for each individual part to be handled. Alternatively, when machining parts with a plurality of different tools, the time required for tool relacement may considerably exceed the actual time required for machining and thus will also influence or determine the rate of production of the machined products.
2. Description of the Prior Art
U.S. patent application Ser. No. 492,652 filed May 9, 1983 by Berg Favot (now abandoned) shows and describes a robot installation in which a robot assembles several parts of a product at the same assembly station. In this known robot installation the movements of the robot during the assembly of a plurality of parts are small, and the assembly of these product parts can be carried out in rapid succession. This improved utilization of the robot in the known robot installation has been achieved by providing the robot with a turret which is indexable and lockable in a number of fixed positions, the turret supporting a number of grippers adapted to handle different parts to be assembled at the assembly station in question. In this known robot installation there are a number of conveyor belts or magazines having feeding devices for feeding forward parts to the operating range of the robot. The known robot is provided with an arm and the turret is connected to the arm by a turnable wrist, the axis of rotation of the turret making an angle, e.g. 45.degree., with the axis of rotation of the wrist. The grippers may be positioned on the turret in such a way that, in one position of the turret, the axis of rotation of the wrist and a symmetry axis or symmetry plane of a gripper are parallel. This facilitates assembly of a product in that only small lifting movements and horizontal transporting movements are required during the actual assembly operation. The number of grippers on the turret may vary; the number of grippers usually being three, four or six. The magazines may be of several different kinds. Magazines for parts which are not symmetrical are suitably of a kind having pallets with guide means for fixing the parts in a certain pattern for orientation of the parts in a definite way so that they may be picked up by the grippers. The known robot installation may include one or more robots and may be completed with other assembly devices, for example machines for inserting and tightening screws.